strangeness nuclear physics nuclei: many body systems of nucleons – can be extended by adding...
TRANSCRIPT
Nuclei with strangeness at J-PARC
Kiyoshi Tanida (Japan Atomic Energy Agency)07/Oct./2015
NUFRA2015@Kemer, Turkey
Strangeness Nuclear Physics• Nuclei: many body systems of nucleons
– Can be extended by adding other flavors: strangeness, charm, ...
S=0 “surface”
Unexplored “space”
Physics interests• New interaction
– Extended nuclear force to flavor SU(3) world– Unified understanding of Baryon-Baryon force –
What is its origin?– Is traditional meson exchange model enough?
Need quark/gluon picture?
• Property of hyperons in nuclei?– Hyperons can mix easily (e.g., LN-SN, LL-XN)
→ Dynamical systems can be made– Effective mass, magnetic moment, ...?
• What happens to nuclei? Impurity effect?– Collective motion? High density matter?
Relation with neutron star• Naively, hyperons are expected to appear in NS
– E.g., Fermi gas model w/o interactionFermi energy of n: MeV at
– , L S-, X- may be important
• Of course, details depend on nuclear interaction– Most of present calculations
expect hyperons at – Can be studied by SNP at J-PARC– Especially, X potential in nuclei
is a key
• Mass, size, ...?
Nuclear & Hadron Physics in J-PARC
Proton Beam
Kaonic nucleusKaonic atom
X ray
K−
Implantation ofKaon and the nuclear shrinkage
K-meson
High Density Nuclear Matter,Nucelar Force
Nuclear & Hadron Physics at J-PARC
K1.8
KL
K1.1BR
High-p
SKS
K1.8BRK1.1
K0 → p0 nnL
COMETBeam line
T-Violation
Free quarks Bound quarks
Why are bound quarks heavier ?
Quark
Mass without Mass Puzzle
Origin of Mass
d
uu
d
s
Pentaquark +
He6
Confinement
e-
m-e conversion
,L X N
ZL, S Hypernuclei
LL, X Hypernuclei
Str
an
ge
ne
ss
0
Hypernuclei
-1
-2
High Density Nuclear Matter, Nucelar Force
Experiments at a glance (not all)
Part I.(selected) Results from
recent experiments
E27, E15, & E13
Deeply bound Kaonic nuclei
Akaishi & Yamazaki, PRC 65 (2002) 044005
BK > 100 MeV??
DISTO (PRL 94, 212303)
FINUDAPRL104, 132502
L(1405) = K-p bound state deeply bound nuclei?Kaon condensation in neutron stars?
No observation in HADES, LEPS, …
E27• Search for K-pp by d(p,K+) reaction
– missing mass spectroscopy
Decay counter to detect ppp from Kpp Lp ppp
Y* peak; data = 2400.6 ± 0.5(stat.) ± 0.6(syst.) MeV/c2
sim = 2433.0 (syst.) MeV/c2
``shift” = - 32.4 ± 0.5(stat.) (syst.) MeV/c2
+2.8-1.6
+2.9-1.7
d(π+, K+) at 1.69 GeV/c (Inclusive spectrum)
10
Gaussian fit
Mass shift of L*(1405) and/or S*(1385)?due to final state interaction?
PTEP 101D03 (2014)
Range counter array(RCA) for the coincidence measurement
• RCA is installed to measure the proton from the K-pp.– K-pp→Λp→pπ-p; K-pp→Σ0p→pπ-γp; K-pp→Ypπ→pπp+(etc.)
• Proton is also produced from the QF processes.– π+``n’’→K+Λπ0, Λ→pπ-
• However, these proton’s kinematics is different.
11
p p
K+
π+
We suppress the QF background by tagging a proton. ☆ Seg2 and 5 are free from QF background.More strongly suppress by tagging two protons.
``K-pp’’-like structure(coincidence) • Broad enhancement ~2.28 GeV/c2 has been observed in
the Σ0p spectrum.• Mass: (BE: )• Width:
• dσ/dΩ``K‐pp’’→Σ0p =
• [Theoretical value: ~1.2]
12
T. Sekihara, D. Jido and Y. Kanada-En’yo, PRC 79, 062201(R) (2009).
<1 proton coincidence probability>π+d→K+X, X→Σ0p <2proton coincidence analysis>
PTEP 021D01 (2015)
Discussion on the ``K-pp’’-like structure • Obtained mass (BE ~ 100 MeV) and broad width are
not inconsistent with the FINUDA and DISTO values. – Theoretical calculation for the K-pp is difficult to
reproduce such a deep binding energy about 100 MeV.– Other possibilities?
• A dibaryon as πΛN – πΣN bound states? (It should not decay to the Λp mode because of I = 3/2.) • Λ*N bound state? • A lower πΣN pole of the K-pp? (The K-pp might have the double pole structure like Λ(1405).)• Partial restoration of chiral symmetry on the KN interaction?
13
H. Garcilazo and A. Gal, NPA 897, 167 (2013).
T. Uchino et al., NPA 868, 53 (2011).
A. Dote, T. Inoue and T. Myo, PTEP 2015 4, 043D02 (2015).
S. Maeda, Y. Akaishi and T. Yamazaki, Proc. Jpn. B 89, 418 (2013).
―
E15
E15 result
• No peak below Kpp threshold
E27 result
• Not a kaonic bound state, but NSp resonance??
PTEP 2015, 061D01
E13 g-ray spectroscopy of hypernuclei• 4
LHe: Charge symmetry breaking in LN interaction?compare the mirror nuclei: 4LHe and 4
LH
• 19LF: First g-ray measurement
on sd-shell hypernuclei– How effective interaction
changes compared to p-shell hypernuclei?
• Hyperball-J– 28 germanium detectors
+ PWO Compton suppressordedicated for hypernuclei
E13 result (1) – 4LH
• Eg=1406±2±2 keV
• Corresponding energy in 4LH: 1090±20 keV
Indication of large charge symmetry breaking
• LN-SN coupling effectwith S mass difference?
arXiv:1508.00376
3He1/2+
1+
0+
4LHe
E13 result (2) – 19LF
𝐅𝚲𝟏𝟗
𝐅𝚲𝟏𝟗
𝐅𝚲𝟏𝟗
𝐅❑𝟏𝟗
annhilation
selectedunbound
𝐁❑𝟏𝟎
Doppler shift not corrected
PreliminarySelected
g.s.Unbound
Analysis in progress
Part II.Coming experiments
E03 & E07
E03 experiment• World first measurement of X rays from X-atom
– Gives direct information on the XA optical potential
• Produce X- by the Fe(K-,K+) reaction, make it stop in the target, and measure X rays.
• Aiming at establishing the experimental method
K- K+
X-
X ray
Fe targetX- (dss)
Fe
X ray
l (orbital angular momentum)
Ene
rgy
(arb
itrar
y sc
ale)
...
...
...
...
l=n-1 (circular state)l=n-2l=n-3
nuclear absorption
X atom level scheme
Z
X
Z
X
X ray energy shift – real partWidth, yield – imaginary part
Successfully used for p-, K-,`p, and S-
K-
K+
X-
Detectors are ready for installationHyperball-J CH
TOF
DC3
DC2DC1FAC
BH2
BAC
FBHPVAC
KURAMA
E07 LL Hypernuclei
Goal: • 10000 stopped X- on emulsion• 100 or more double-L HN events• 10 nuclides
Chart of double-L hypernuclei
Hybrid emulsion method
Xp LL stay in thenucleus ( ~10 %)
Production of LL-nuclei by fragmentation
Systematics of LL binding energy• LL binding energy may be different for each nucleus
– For example by hyperon mixing effect
p n L
6LLHe
p n L
5LLHe
p n X
Suppressed Enhanced
p n X
E03/07 run plan in 2015-2017• Test beam for 3 days in October 2015
– Confirm detector performance– Measurement of beam profile
• Installation of KURAMA spectrometer from January– Commissioning beam time in Spring.
• E07 beam time in 2016 with full statistics• E03 beam time is expected after E07.
– Likely in early 2017.– We will have more than 1x1011 K- on target
(10% of proposal)– Observation of X-atomic X ray should be possible,
though finite shift/width may not be observable.
Extended Hadron Hall
Details under discussion
Even further...
Summary• Search for deeply bound Kaonic nuclei (E27, E15)
– Mass shift of L*(1405) and/or S*(1385)?– Hint of deeply bound “Kpp”-like structure observed in d(p+,K+)
reaction, but not observed in (K-,n) reaction– Kaonic nuclei?, SpN?, OR, something else?
• E13: g-ray spectroscopy of hypernuclei– g-ray from 4
LHe observed large charge symmetry breaking
– Several g rays are seen from 19LF (analysis in progress)
• Coming experiments – on doubly strange systems– E03: X-ray spectroscopy of X atom– E07: Systematic study of double-L hypernuclei in emulsion – Expect to run in 2016 & 2017
BACK UPS
Calibration: p(π+, K+)Σ+ at 1.69 GeV/c
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Σ+
Σ(1385)+
Zoom
M = 1381.1 ± 3.6 MeV/c2
Γ = 42 ± 13 MeVPDG: M = 1382.8 ± 0.35 MeV/c2, Γ = 36.1 ± 0.7 MeV
Data:
θπK dependence( + data, ―sim)
33
< Peak position >+ data+ simulation
Y* peak positions are shifted to the low mass side for all scattering angles.
HADES experiment for Λ(1405)
34
M = 1385 MeV/c2,Γ = 50 MeVS-wave Breit Wigner function
The peak position of Λ(1405)is shifted to low-mass side.
E19 ExperimentSearch for pentaquark, Q+
• There are two kinds of usual hadrons (= feel strong force)– Baryon (Fermion): Meson (Boson):
– Color neutrality required from QCDBut they are not the only cases Exotic hadrons
– Pentaquark = 5 quarks
Pentaquark Q+
• First reported in 2003 by LEPS collaboration
• Both positive and negative results– Still controversial
• Mysteries– Why so narrow?
G < 1 MeV– Spin-parity?– What’s that
eventually?
T. Nakano et al.,PRC79 (2009) 025210
High resolution search by p(p-,K-)Q
• A good resolution:~2 MeV (FWHM)– thanks to SKS
• Why high resolution?– Good S/N ratio– Width measurement
Almost certainly G < 1 MeV
• Typical resolution in the past ~ 10 MeV– No high resolution search– There is a good chance
Moritsu et al., PRC90 (2014) 035205
• Spectra well represented by known backgrounds
at both energies
Upper limit on decay width• Based on an effective
Lagrangian approach:Hyodo et al., PTP128 (2012) 523
• Upper limit:
0.36 MeV for ½+
1.9 MeV for ½-
For most conservative cases, taking theoretical uncertainties into account
• Comparable to DIANA result
E10
41
),(),( KK Double Charge-Exchange (DCX)
N~Z (I=0 or 1/2)
N>>Z (I=3/2 or 2)
ordinary nuclei
J-PARC E10
Non Charge-Exchange (NCX)
hyperfragmentsby emulsions exp.
L-hypernuclei
),(),( KK
Neutron rich hypernuclei via (p-,K+) reaction
ΛN-ΣN Mixing in Λ Hypernuclei
if core isospin=0
L SA(I=0) A(I=0)
if core isospin0
L SA(I0) A(I0)
OK!
• Smaller mass difference~300 MeV in DN vs ~80 MeV
• Suppressed in I=0 core– Stronger mixing expected
for neutron rich hypernuclei
Result
• No peak observed
• ds/dW< 1.2 nb/sr– 10 times
smaller than10
LLi– Does it really
bind?
PLB 729 (2014) 39